This article shows you how to login to a Salesforce production environment.
When you've been setup as a user in your organisation's Salesforce instance you will receive an email triggered by your system administrator, the email will provide a link that allows you to set a password and login to your environment.
After setting your password and logging in initially, you can now access Salesforce from any device with an internet connection by going to this link - https://login.salesforce.com.
Your username in most cases will be your email address and your password will be whatever you've set it to be.
Google Chrome is the recommended browser for accessing Salesforce.
Bookmark the page by clicking on the Star Icon in the URL window and/or create a desktop link to the page by dragging and dropping the link to your desktop.